1. Field of the Invention
The present invention relates to semiconductor methods, and more particularly to semiconductor methods related to amorphous carbon layers.
2. Description of the Related Art
With advances in electronic products, semiconductor technology has been applied widely in manufacturing memories, central processing units (CPUs), liquid crystal displays (LCDs), light emitting diodes (LEDs), laser diodes and other devices or chip sets. In order to achieve high integration and speed targets, dimensions of semiconductor integrated circuits have been reduced and various materials, such as amorphous carbon, have been proposed along with techniques for overcoming manufacturing obstacles associated with these materials.
Amorphous carbon is a new material used in semiconductor technology. An amorphous carbon layer can be formed substantially conformally over a semiconductor structure over a substrate by a chemical vapor deposition (CVD) process. In addition, the amorphous carbon layer has a desired thermal stability even between about 400° C. and about 550° C. The amorphous carbon layer will not crack in this temperature range. (The temperature range would result in cracking of organic material, such as photoresist.) Further, the amorphous carbon layer can be removed by an oxygen plasma that is used to remove a photoresist layer as well. Thus, an amorphous carbon layer can serve as a hard mask and/or anti-reflection coating (ARC) layer under a photoresist layer to form a via/contact plug in nanometer level semiconductor technology.
FIGS. 1A-1C are schematic cross-sectional views illustrating a process for formation of a via/contact plug.
Referring to FIG. 1A, an oxide layer 110, an amorphous carbon layer 120, an oxynitride layer 130 and photoresist layer 135 are sequentially formed over a substrate 100. The photoresist layer 135 includes an opening 137 therein for forming a via/contact hole in FIG. 1B.
A portion of the amorphous carbon layer 120 and a portion of the oxynitride layer 130 are removed by an etch process to form an opening 140 within the amorphous carbon layer 120a as shown in FIG. 1B. The photoresist layer 135 is then removed by a photoresist removal process. For some semiconductor processes, the removal of the photoresist layer 135 and the partial removals of the amorphous carbon layer and oxynitride layer for forming the opening 140 are performed by the same etch process.
Referring to FIG. 1C, the oxynitride layer 130a and the amorphous carbon layer 120a are removed. The amorphous carbon layer 120a can be removed by oxygen plasma. A metal layer 150 is then formed within the opening 140.